A column is a vertical structural element that distributes the load from a building’s beam and slab to the substructure and at last to the foundation. The axial loads of buildings are handled by columns under compression. Columns are crucial to provide strength to a multi-story structure, and the collapse of even one column may result in the structure falling immediately.
Now that we have already discussed “what is column”, we are going to talk more about different types of columns. We are also going to understand the difference between strut and column. Before moving forward, let’s understand the use of creating columns in construction.
Use of Column in Construction
Columns play a key role in providing support to the structure. The following are the common uses of column in construction:
- Columns are vertical structures that carry compressive stress from the top to the bottom.
- Columns support both the floor and the columns on the upper floors.
- The ground floor columns must be strong enough to support the total weight of all floors above them.
- Columns should be placed in the same manner throughout all levels to provide the best support. This would make the structure’s lowest group of columns more stable.
- Before selecting a good design, structural engineers must check the column’s weight capacity. The vertical forces acting on the column will influence its design.
Columns are also helpful in providing safety against earthquakes and winds. Hence, the impact of lateral stress induced by earthquakes and winds must also be considered while deciding on column size and dimensions.
Types of Columns in Construction
Columns are categorized on the basis of factors like types of reinforcement, types of loading, slenderness ratio, shape, and construction material. Let’s have a look at the different types of columns commonly used in construction.
Columns Based on the Type of Reinforcement
- Tied Column
It uses strengthened cement concrete with closely spaced tie bars as the primary longitudinal support. The majority of the columns in the structure are linked columns and hence fall under the category of RCC Column. The ties can only be spaced far enough apart to not interfere with the formation of concrete while remaining close enough to prevent rushing failure between them. If the ties are too far apart, the column will fail due to shear and rushing.
- Spiral Column
This is a unique type of RCC column. The longitudinal bars of this type of column are enclosed by closely spaced, constantly coiled spiral column reinforcement. The role of spiral reinforcement is to defer axial load failure while providing lateral constraints to hence enhance column strength. These columns have six longitudinal main bars in a spirally reinforced column for column reinforcement.
- Composite Column
A composite column is reinforced with structural steel pipes or sections. Composite columns are fireproof and strong, despite their narrow cross-section. These types of columns are commonly used in truss projects to protect steel against corrosion.
Columns Based on Types of Loading
- Axially Loaded Column
Axially loaded columns are subjected to vertical axial loads that act at the column’s center of gravity. These columns are rarely used because vertical loads cannot be aligned with the column’s cross-sectional center of gravity. Axially loaded columns are internal columns in multi-story constructions that bear symmetrical loads from floor slabs in all directions.
- Column with Uniaxial Eccentric Loading
Vertical loads in uniaxially eccentric loaded columns act eccentrically on either the X or Y axis of the column cross-section, rather than parallel to the column’s center of gravity. These sorts of columns include edge columns and columns that are firmly linked to a beam.
- Column with Biaxial Eccentric Loading
There are a few columns in which the vertical load of the column does not coincide with the center of gravity of the column cross-section; such columns are said to be biaxially eccentrically loaded. Also, the load does not act on either axis (X or Y). Biaxial Eccentric Loaded columns have securely coupled beams at right angles at the top.
Columns Based on Their Slenderness Ratio
- Short Column
If the slenderness ratio is less than 12, the column is considered short. Short columns collapse owing to crushing, which leads to compression failure.
- Long Column
Long columns have a slenderness ratio of more than 12. Long columns fail from buckling or bending, whereas short columns fail from crushing. Based on the shape of the RCC column, which is circular.
Columns Based on Their Shape
- Circular Column
These columns have a circular cross-section and are primarily utilized for structural support and elevation. Circular columns are commonly used in piling and structural elevation for aesthetic purposes. Circular columns are more resistant to bending than square or rectangular columns.
- Square or Rectangular Columns
Rectangular or square-shaped columns are easier to make and cast than circular RCC columns because they are easy to shutter and can withstand pressure before concrete sets.
- L-Shaped Column
L-shaped columns, which are similar to rectangular and square columns, are commonly used in the corners of boundary walls.
- T-Shaped Column
It is used according to the structural design. T-shaped columns are widely used in bridge and retaining wall construction.
Apart from the above-mentioned types, columns can also be categorized on the basis of Building Materials. Columns can be reinforced concrete, steel, wood, brick, block, or stone, depending on the building materials used in their construction.
Difference Between Strut and Column
The main difference between a strut and a column is that a column is a vertical part designed to support axial or longitudinal loads, on the other hand, the strut is a horizontal/inclined/vertical component that can support axial or longitudinal loads. Columns are supported by fixed supports on both ends, whereas struts are supported by hinged or pinned joints on both ends, this is the reason why struts are frequently used in trusses.
Columns typically fail because of buckling, whereas struts fail due to crushing. Columns are more thin than struts. Columns can support only compressive and tensile loads.
